Project description:Pathogenic heterozygous missense mutations in the DNM1 gene result in a novel form of epileptic encephalopathy. DNM1 encodes for the large GTPase dynamin-1, an enzyme with an obligatory role in the endocytosis of synaptic vesicles (SVs) at mammalian nerve terminals. Pathogenic DNM1 mutations cluster within regions required for its essential GTPase activity, implicating disruption of this enzyme activity as being central to epileptic encephalopathy. We reveal that the most prevalent pathogenic mutation in the GTPase domain of DNM1, R237W, disrupts dynamin-1 enzyme activity and SV endocytosis when overexpressed in central neurons. To determine how this dominant-negative heterozygous mutant impacted cell, circuit and behaviour when expressed from its endogenous locus, we generated a mouse carrying the R237W mutation. Neurons isolated from heterozygous mice displayed dysfunctional SV endocytosis, which translated into altered excitatory neurotransmission and seizure-like phenotypes. Importantly, these phenotypes were corrected at the cell, circuit and in vivo level by the drug, BMS-204352, which accelerates SV endocytosis in wild-type neurons. This study therefore provides the first direct link between dysfunctional SV endocytosis and epilepsy, and importantly reveals that SV endocytosis is a viable therapeutic route for monogenic intractable epilepsies.
Project description:Scn1b null mice are a model of a severe developmental and epileptic encephalopathy called Dravet Syndrome (DS). The goal of this study was to identify changes in gene expression between Scn1b wild-type and Scn1b null mice before seizure onset (postnatal day 10)
Project description:We generated cerebral organoids from genetically engineered human embryonic stem cells (hESCs), modeling the devastating WOREE syndrome (DEE28), as a prototype for genetic epileptic encephalopathies (EEs). Transcriptome analysis of mutated organoids compared to the WT revealed molecular changes related to both early infantile EEs and specifically to WOREE syndrome.
Project description:Scn1b null mice are a model of a severe developmental and epileptic encephalopathy called Dravet Syndrome (DS). The goal of this study was to identify changes in gene expression between Scn1b wild-type and Scn1b null mice before seizure onset (postnatal day 10) in cortical layer VI, a region known to have differences in excitability in Scn1b null mice. RNA-Seq identified 21 genes, primarily extracellular matrix genes, which were differentially expressed between the two genotypes.
Project description:Epilepsy causes altered gene expression; transient adenosine treatment inhibits progression of epileptogenesis Hippocampus of epileptic rat is hypermethylated compared to naïve; adenosine treatment causes hypomethylation Metylation state in epileptic rats (9 weeks post kainic acid induced status epilepticus) was compared to naïve (untreated) rats and epileptic rats treated with adenosine for 5 days
Project description:Epilepsy accompanying cognitive impairment has been verified by accumulating clinical cases, but the mechanism remains unclear. Here, we discover that persistent epileptic seizures impaired the ability of mice to recognize either novel objects or novel locations at 6 months old but not at 2 months old by utilizing the spontaneous epilepsy model of Cdh5-CreERT2; CDK5f/f mice after tamoxifen treatment. To the best of our knowledge, this is the first report that the levels of synapse-related proteins, such as NMDA receptors (NR1 and NR2B), PSD95, and phosphorylation of CaMKII, are progressively decreased during epileptic seizures in the hippocampus of spontaneous epileptic mice. Notably, we also found that valproate (VPA) augment synapse-related genes and protein expression and ameliorate progressive cognitive impairment. Hence, our study describes a mechanism of cognitive deficits in epilepsy and identifies new effects of VPA on synapses, which provides new insights into preventive or therapeutic interventions for epileptic cognitive deficits.
Project description:Dravet syndrome (DS) is a severe epileptic encephalopathy caused by heterozygous loss-of-function mutations in the SCN1A gene, indicating a haploinsufficient genetic mechanism underlining this pathology. Here, we tested whether dCas9-mediated Scn1a gene activation could rescue Scn1a haploinsufficiency and restore physiological levels of its gene product, the Nav1.1 voltage-gated sodium channel. We screeened sgRNAs for their ability to stimulate Scn1a gene transcription in association with the dCas9 activation system. Interestingly, we identified one single sgRNA able to significantly increase Scn1a gene expression levels in cell lines as well as in primary neurons, with high specificity. Accordingly, levels of Nav1.1 protein were sufficiently augmented to potentiate firing ability of wild-type immature GABAergic interneurons. A similar effect in activating the Scn1a transcription was elicited in Dravet GABAergic interneurons rescuing their dysfunctional properties. To determine whether this approach could have therapeutic effect, we packaged adeno-associated viruses with the Scn1a-dCas9 activation system and showed their ability to ameliorate the febrile epileptic crises in DS mice. Our results pave the way for exploiting the dCas9-based gene activation as an effective and targeted approach to DS and other similar disorders resulting from altered gene dosage.
Project description:A 6-year-old boy, second son of healthy parents affected with epileptic encephalopathy of neonatal onset. Pregnancy with gestational diabetes controlled with diet. Delivery was uneventful. Since 48 hours of life, he presented episodes of cyanosis, generalized hypertonia, and tonic asymmetric postures followed by apnea. Video-EEG at 5 days of life showed bilateral and asynchronous spike-and-wave. Seizures were refractory to phenobarbital but were controlled with phenytoin. Since 3 months of age, he presented with startle episodes without EEG correlate related to the wake and sleep transition together with dystonic postures. One month later, epileptic spasms without hypsarrhythmia were observed. No response to levetiracetam and valproic acid but stopped after lacosamide (LCS) treatment was initiated (11 months of age). Metabolic tests (including CSF studies), karyotype, and brain MRI were normal. Epileptic encephalopathy gene panel was negative including hyperekplexia related genes. Progressive increase of TSH was treated with oral L-t4. At 20 months he presented recurrence of spasms that were controlled with LCS dose adjustment. V-EEG: abnormal background activity and paroxysmal multifocal discharges that showed activation and generalization during sleep. After several years of good seizure control, LCS was discontinued. He suffered from decompensation of seizures with febrile viral infection and at 5 years of age he presented startle episodes associated to auditory stimulus without EEG correlate, but during sleep, he presented epileptic spasms with EEG correlate. Treatment with vigabatrine was initiated with a clinical and EEG improvement. At physical exam he presents severe axial hypotonia without head control. Hypertonia of 4 limbs with dystonic movements of upper limbs. No hand use and is not able to sit or crawl. No development of expressive language.GMFCS: V. No development of expressive language. Last v-EEG monitoring showed bilateral polyspike discharges and clinical spasms in polygraph recording without any clear EEG correlate. Whole exome sequencing was performed and partial exon 7 duplication, heterozygous variant, in KCNQ2 was found. aCGH study detected several CNV in genes associated to neural functions (losses: LRRC55, PCDH9, NALCN, RYR3, ELAVL2, CDH13, ATP1A2, SLC17A5, ANO3. Gains : PCDH19, TENM1, EFNA5).